Why are objects in freefall considered Weightless?

Answer 1

Because the object's inertial motion is equal to the gravitational acceleration.

Weight equals mass times gravitational acceleration (W=mg), so you would feel weightless, but your mass stays the same.

Answer 2

yes

Weightlessness in Orbit

Astronauts on the orbiting space station are weightlessbecause... a. there is no gravity in space and they do not weigh anything. b. space is a vacuum and there is no gravity in a vacuum. c. space is a vacuum and there is no air resistance in a vacuum. d. the astronauts are far from Earth's surface at a location where gravitation has a minimal affect.

Earth-orbiting astronauts are weightless for the same reasons that riders of a free-falling amusement park ride or a free-falling elevator are weightless. They are weightless because there is no external contact force pushing or pulling upon their body. In each case, gravity is the only force acting upon their body. Being an action-at-a-distance force, it cannot be felt and therefore would not provide any sensation of their weight. But for certain, the orbiting astronauts weigh something; that is, there is a force of gravity acting upon their body. In fact, if it were not for the force of gravity, the astronauts would not be orbiting in circular motion. It is the force of gravity that supplies the centripetal force requirement to allow the inward acceleration that is characteristic of circular motion. The force of gravity is the only force acting upon their body. The astronauts are in free-fall. Like the falling amusement park rider and the falling elevator rider, the astronauts and their surroundings are falling towards the Earth under the sole influence of gravity. The astronauts and all their surroundings - the space station with its contents - are falling towards the Earth without colliding into it. Their tangential velocity allows them to remain in orbital motion while the force of gravity pulls them inward.

Many students believe that orbiting astronauts are weightless because they do not experience a force of gravity. So to presume that the absence of gravity is the cause of the weightlessness experienced by orbiting astronauts would be in violation of circular motion principles. If a person believes that the absence of gravity is the cause of their weightlessness, then that person is hard-pressed to come up with a reason for why the astronauts are orbiting in the first place. The fact is that there must be a force of gravity in order for there to be an orbit.

One might respond to this discussion by adhering to a second misconception: the astronauts are weightless because the force of gravity is reduced in space. The reasoning goes as follows: "with less gravity, there would be less weight and thus they would feel less than their normal weight." While this is partly true, it does not explain their sense of weightlessness. The force of gravity acting upon an astronaut on the space station is certainly less than on Earth's surface.

Still other physics students believe that weightlessness is due to the absence of air in space. Their misconception lies in the idea that there is no force of gravity when there is no air. According to them, gravity does not exist in a vacuum. But this is not the case. Gravity is a force that acts between the Earth's mass and the mass of other objects that surround it. The force of gravity can act across large distances and its affect can even penetrate across and into the vacuum of outer space. Perhaps students who own this misconception are confusing the force of gravity with air pressure. Air pressure is the result of surrounding air particles pressing upon the surface of an object in equal amounts from all directions. The force of gravity is not affected by air pressure. While air pressure reduces to zero in a location void of air (such as space), the force of gravity does not become 0 N. Indeed the presence of a vacuum results in the absence of air resistance; but this would not account for the weightless sensations. Astronauts merely feel weightless because there is no external contact force pushing or pulling upon their body. They are in a state of free fall.

- freedark-

disinon

Answer 3

Objects in free fall aren't just *considered* weightless, they are! If you jump out of a plane, you won't feel your own weight, as you are accelerating at the same speed as the gravitational acceleration. Einstein used this fact as the basis of his Theory of General Relativity, where a gravitational attraction is identical to an acceleration.

Answer 4

Weight is a measure of the "downward" force an object exerts on the earth. So if an object is in freefall, it does not exert "downward" force. Think of it like standing on your bathroom scale. If you are not falling, you have a weight, ie. there is pressure exerted down on the scale. If you are freefalling and standing on your scale, the scale will read 0, ie you are not putting pressure on the scale.

Just don't get confused between weight and mass

Answer 5

Weight is the product of mass and acceleration W= ma. If acceleration a is zero then weight W= m0 = 0 is zero, while mass is not. Acceleration can be zero while mass is not.